BUT here a very natural, and very material, question arises: how are these customs or maxims to be known, and by whom is their validity to be determined? The answer is, by the judges in the several courts of justice. They are the depositary of the laws; the living oracles, who must decide in all cases of doubt, and who are bound by an oath to decide according to the law of the land. Their knowlege of that law is derived from experience and study; from the "_viginti annorum lucubrationes_," which Fortescue[n] mentions; and from being long personally accustomed to the judicial decisions of their predecessors. And indeed these judicial decisions are the principal and most authoritative evidence, that can be given, of the existence of such a custom as shall form a part of the common law. The judgment itself, and all the proceedings previous thereto, are carefully registered and preserved, under the name of _records_, in publick repositories set apart for that particular purpose; and to them frequent recourse is had, when any critical question arises, in the determination of which former precedents may give light or assistance. And therefore, even so early as the conquest, we find the "_praeteritorum memoria eventorum_" reckoned up as one of the chief qualifications of those who were held to be "_legibus patriae optime instituti_[o]." For it is an established rule to abide by former precedents, where the same points come again in litigation; as well to keep the scale of justice even and steady, and not liable to waver with every new judge's opinion; as also because the law in that case being solemnly declared and determined, what before was uncertain, and perhaps indifferent, is now become a permanent rule, which it is not in the breast of any subsequent judge to alter or vary from, according to his private sentiments: he being sworn to determine, not according to his own private judgment, but according to the known laws and customs of the land; not delegated to pronounce a new law, but to maintain and expound the old one. Yet this rule admits of exception, where the former determination is most evidently contrary to reason; much more if it be contrary to the divine law. But even in such cases the subsequent judges do not pretend to make a new law, but to vindicate the old one from misrepresentation. For if it be found that the former decision is manifestly absurd or unjust, it is declared, not that such a sentence was _bad law_, but that it was _not law_; that is, that it is not the established custom of the realm, as has been erroneously determined. And hence it is that our lawyers are with justice so copious in their encomiums on the reason of the common law; that they tell us, that the law is the perfection of reason, that it always intends to conform thereto, and that what is not reason is not law. Not that the particular reason of every rule in the law can at this distance of time be always precisely assigned; but it is sufficient